U.S. Pat. No. 4,615,385, issued same assignee as the instant application, illustrates, in FIGS. 1-4 thereof, a highly efficient heat exchanger construction with numerous advantages over those heretofore known in any of a variety of uses. In that heat exchanger embodiment, header plates and separate tanks secured thereto are eliminated in favor of tubular headers which serve as a combination header and tank. The headers are nominally cylindrical and are parallel to one another. Each header includes spaced slots which are adapted to receive respective ends of oval tubes which, in turn, conduct one heat exchange fluid from one header to the other. Without more, flow of such heat exchange fluid is parallel flow; and in many instances, that is all that is required.
However, there are various uses of such a basic heat exchanger structure that require multiple passes of the fluid between the headers. In order to accomplish multiple pass flow within the heat exchanger, one or more baffles are located in one or both of the tubular headers between the ends thereof.
In order to provide interior baffles, some attempts have been made to insert slug or cap-like cylindrical structures into the headers from either end thereof. This approach has not been altogether satisfactory because the baffle must be precisely located prior to the formation of tube-receiving slots in the header, and if not properly located, may obstruct the slot-forming process. Furthermore, to prevent shifting of the baffle once in place, it may be necessary to perform a bonding operation prior to the ultimate bonding operation wherein the tubes are, for example, brazed within the slots in the headers.
To avoid these and other difficulties, other proposals have been advanced. Generally these include forming some sort of a partial, transverse slot across the header at the desired baffle location. This allows the baffle to be inserted into the header and held at precisely the proper location substantially simultaneously with the formation of the entire heat exchanger so that but a single bonding operation need be employed and positive placement of the baffle assured. Furthermore, because the baffle need not be inserted until well after the slot-forming operation, there is no possibility that the baffle will interfere with that operation.
At the same time, this method generally requires that the header periphery be cut through a length equal to an arc length of at least 180.degree. , and frequently more, which in turn can undesirably weaken the header.
The present invention is directed to overcoming one or more of the above problems.